A game mode featured in nearly every shooter (simulator or FPS) that allows you to blow the living crap out of your opponents. It was popularized by Doom and pretty much made it a requirement for every shooter in the market after. These days multiple modes of deathmatches (like Capture the Flag and Team games) exist.

Find a buddy, start a game, and beat the living snot out of him. Do it again in another way. Repeat until you have the most kills. That's the basics of DeathMatch.

When two individuals agree to a fight to the death. This is a mode of settling conflicts which is usually neglected in modern society. A deathmatch is always an unarmed fight, otherwise it would be called a duel.

When Carl refused to leave my house when I asked, I challenged him to a deathmatch.